Don't Breathe Yet

Exposure to diesel exhaust for a couple of hours a day is enough to give birth to blood vessels that feed tumours. Experiments on mice showed that exposure to diesel exhaust caused a six-fold increase in blood vessel formation in diseased mice and a four-fold increase in healthy mice breathing diesel fumes. There was no such increase in mice breathing filtered air. The exhaust activated a chemical signal and a protein associated with new blood vessel development. It lowered the activity of an enzyme that can suppress tumour growth.

Source : Down to Earth , October 2009